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SELECT * FROM LIMIT 1; is really slow - Mailing list pgsql-hackers
From David Blasby
Subject SELECT * FROM LIMIT 1; is really slow
Date
Msg-id 40B5057F.2000007@refractions.net
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Responses Re: SELECT * FROM LIMIT 1; is really slow  (Gaetano Mendola <mendola@bigfoot.com>)
Re: SELECT * FROM
LIMIT 1; is really slow  (Tom Lane <tgl@sss.pgh.pa.us>)
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I have a table with about 16,000,000 rows in it.

When I do a:

SELECT * FROM <table> LIMIT 1;

it takes about 10 minutes (thats about how long it takes to do a full 
sequential scan).

I had originally thought that there might be a large number of 
"wasted/retired" tuples in the table so I "vacuum analysed" the 
database.  It had no effect.  I had a "vacuum full" going on the table 
for 17 hours before I killed it.

Any idea why its so slow? It used to be instant.

dave

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